document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=654493>Question 654493</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the value of k so that the line containing the points (-4,k) and (8,-4) is perpendicular to the line y=2/5x+4. If you could explain how I should start this problem. I thought if it is perpendicular I would use the opposite reciprocol, but considering I have an unknown variable(k) not quite sure what to do with it. Thanks for your time!  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #408751 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=408751\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find the value of k so that the line containing the points (-4,k) and (8,-4)<BR>\n" );
document.write( " is perpendicular to the line y=2/5x+4.<BR>\n" );
document.write( ":<BR>\n" );
document.write( "The slope of the given equation: m1 = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F5 ALIGN=MIDDLE  ALT=\"2%2F5\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Find the slope (m2) of the given coordinates<BR>\n" );
document.write( "The slope formula m = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28y2-y1%29%2F%28x2-x1%29 ALIGN=MIDDLE  ALT=\"%28y2-y1%29%2F%28x2-x1%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Assign the values as follows<BR>\n" );
document.write( "x1=-4, y1=k<BR>\n" );
document.write( "x2=8, y2=-4<BR>\n" );
document.write( "m2 = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-4-k%29%2F%288-%28-4%29%29 ALIGN=MIDDLE  ALT=\"%28-4-k%29%2F%288-%28-4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28%28-4-k%29%29%2F12 ALIGN=MIDDLE  ALT=\"%28%28-4-k%29%29%2F12\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( ":<BR>\n" );
document.write( "We know the slope relationship between perpendicular lines is m1*m2 = -1<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F5 ALIGN=MIDDLE  ALT=\"2%2F5\"   DISABLED_style= \"max-width:90%; height:auto;\" >*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28%28-4-k%29%29%2F12 ALIGN=MIDDLE  ALT=\"%28%28-4-k%29%29%2F12\"   DISABLED_style= \"max-width:90%; height:auto;\" > = -1<BR>\n" );
document.write( "cancel 2 into 12<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F5 ALIGN=MIDDLE  ALT=\"1%2F5\"   DISABLED_style= \"max-width:90%; height:auto;\" >*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28%28-4-k%29%29%2F6 ALIGN=MIDDLE  ALT=\"%28%28-4-k%29%29%2F6\"   DISABLED_style= \"max-width:90%; height:auto;\" > = -1<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28%28-4-k%29%29%2F30 ALIGN=MIDDLE  ALT=\"%28%28-4-k%29%29%2F30\"   DISABLED_style= \"max-width:90%; height:auto;\" > = -1<BR>\n" );
document.write( "multiply both sides by -30, also gets rid of all those negatives<BR>\n" );
document.write( "4 + k = 30<BR>\n" );
document.write( "k = 30 - 4<BR>\n" );
document.write( "k = 26<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Use this value for y1, find the slope (m2) of the new equation,<BR>\n" );
document.write( "Find the equation using the point/slope formula, y-y1 = m(x-x1)<BR>\n" );
document.write( "See that it is perpendicular to y = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F5 ALIGN=MIDDLE  ALT=\"2%2F5\"   DISABLED_style= \"max-width:90%; height:auto;\" >x + 4 </SPAN>\n" );
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